1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, printer or the like, and more particularly, it relates to an image forming apparatus wherein a sheet re-feeding path for the double-surface recording is detachably provided.
2. Related Background Art
In a conventional image forming apparatus such as, for example, a double-surface recording printer (which can record images on both surfaces of a sheet), as shown in FIG. 1, one by one a sheet P is fed from a cassette 1, an image is recorded on the sheet P at an image forming station 3, and the recorded image is fixed on the sheet P at a fixing station 4. Thereafter, the sheet P is ejected or discharged through a sheet feeding path 5 or is deflected by a flapper 6 to be directed to ejector rollers 7 where the sheet is switched-back toward a sheet re-feeding path 8. In the latter case, the sheet passes through the sheet re-feeding path 8 and then is turned over and fed again to the image forming station 3, where an image is recorded on the other surface of the sheet. Thereafter, the image is fixed on the other surface of the sheet at the fixing station 4 and then the sheet P is ejected through the sheet feeding path 5. With this arrangement, in the conventional image forming apparatus, a sheet re-feeding path for the double-surface recording constituted by the flapper 6, ejector rollers 7 and sheet re-feeding path 8 was integrally incorporated into the apparatus, with the result that the sheet re-feeding path for the double-surface recording could not be detached from the apparatus.
Thus, in the past, a single-surface recording printer and a double-surface recording printer were manufactured separately or independently and were not interchangeable to each other.
However, (i) after a user bought a single-surface recording printer, when he desires or needs to perform double-surface recording, there arises a problem that he must newly buy a double-surface recording printer, or (ii) if a user needs to obtain a great number of prints, he must increase a capacity of the cassette into which the sheets are stacked, or must increase a capacity of an ejector tray onto which the recorded sheets are collected. Also, in this case, there arises a problem that he must buy another new printer having the larger capacity.